Who Defines the Margin? Dermatologist-Led Dermoscopy versus Plastic Surgeon–Led Clinical Assessment in Non-Melanoma Skin Cancer

Objectives: To compare preoperative diagnostic concordance and histopathological margin outcomes between two pathways for clinically suspected nonmelanoma skin cancer: assessment and margin marking by dermatologists using clinical examination and dermoscopy versus assessment and marking by plastic surgeons using clinical examination and guideline-based risk stratification. All excisions were performed by the same plastic surgery team.Materials and Methods: This single-center, nonrandomized, prospective cohort study included patients presenting independently to Dermatology or to Plastic Surgery from December 2023 through December 2024 for primary excision of clinically suspicious lesions. After exclusions, 184 patients were analyzed: 100 in the dermatology pathway and 84 in the plastic surgery pathway. Comparisons used the Mann–Whitney U, chi-square, or Fisher exact test. Multivariable logistic regression adjusted margin positivity for age, tumor type, and anatomical site.Results: Diagnostic concordance was higher in dermatology pathway (63/70, 90.0%) than in plastic surgery pathway (41/60, 68.3%; risk difference 21.7 percentage points, 95% CI 8.0–35.4; OR 4.17, 95% CI 1.61–10.80; p=0.004). Positive margins occurred in 11/100 (11.0%) and 11/84 (13.1%), respectively (OR 0.82, 95% CI 0.34–2.00; p=0.820), with no association after adjustment (OR 0.86, 95% CI 0.34–2.16; p=0.747). The nearest lateral margin was wider in dermatology pathway (median 3.20 vs. 2.70 mm; p=0.027), but the difference became non-significant after excluding involved margins (p=0.053). Deep margins and tumor thickness were similar.Conclusion: Dermatologist-led preoperative assessment incorporating dermoscopy was associated with greater diagnostic concordance and in the primary analysis, wider lateral histopathological margins but not with a lower positive-margin rate. Because all excisions were performed by one surgical team, specialist preoperative assessment contributes principally to lesion characterization rather than to surgical clearance.